Rock (Likely Sedimentary)

Weathered sandstone or quartzite cobble

Quartz-rich sandstone; possibly metamorphosed to quartzite

Weathered sandstone fragment

Quartz-rich sandstone, likely arkose or lithic sandstone

Tumbled kambaba jasper (likely)

Kambaba jasper, a silica-rich microcrystalline quartz aggregate, commonly containing fossilized cyanobacterial structures and dark green amphibole/pyroxene minerals

Sandstone (likely Quartzite-rich)

Arenite (primarily SiO2)

Chert (Nodule/Pebble)

Chert (Silicon Dioxide, SiO2)

Weathered iron-rich rock, likely ironstone or limonite-bearing concretion

Ironstone/limonite-rich concretion; mainly goethite FeO(OH), hematite Fe₂O₃, and hydrated iron oxides

Sandstone (likely with Quartz Veining)

Arenite (primarily SiO2)

Likely limestone fragment

Limestone, predominantly calcite (CaCO₃)

Biotite-bearing schist

Mica schist, chiefly quartz–feldspar–biotite (phyllosilicate-rich)

Weathered brown rock fragment (likely sandstone or iron-stained quartzite)

Indeterminate; probable quartz-rich sandstone, SiO₂-dominated

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Sandstone (likely Quartzose Sandstone with mineral staining)

Arenite (composed mainly of SiO2)

Sandstone (likely Quartzose Sandstone)

Arenite (primarily SiO2)

Ironstone (likely Limonite or Goethite)

Ferruginous sedimentary rock (FeO(OH)·nH2O)

River Cobble (Mixed Lithology)

Clastic Sedimentary Rock (Silicified Siltstone or Wacke)

Quartz crystal-bearing rock

Quartz (SiO₂), likely a milky/clear quartz vein specimen

Quartz geode (likely chalcedony-lined geode)

Silica geode: microcrystalline quartz/chalcedony with drusy quartz (SiO₂), possibly iron-oxide staining

Likely slate or fine-grained metamorphic rock

Slate; predominantly microcrystalline quartz, mica, and clay minerals

Mixed rock and mineral specimen collection

Multiple species, likely quartz (SiO₂), calcite (CaCO₃), feldspar, chert, and assorted volcanic/sedimentary rocks

Mixed rock and mineral specimen collection

Varied silicate, carbonate, and oxide minerals; individual identification is not possible from this group photograph

Rounded pale river pebble, likely chert or quartz-rich stone

Most likely microcrystalline silica (chert, SiO₂) or fine-grained quartzite; identification is uncertain from the photograph

Sandstone (Quartzite Pebble)

Arenite / Metamorphosed Sandstone (SiO2)

Brown Pebble (River Rock)

Indeterminate (Likely Silicon Dioxide / Quartz-rich)

Fossiliferous Chert or Limestone

Sedimentary rock containing fossilized marine invertebrates (likely crinoid stems or bryozoans)

Rounded iron-rich pebble

Likely ferruginous sandstone or ironstone; exact identification requires testing

Pyrite-bearing metamorphic rock (likely schist or quartzite)

Pyrite (FeS₂) in a quartz-rich host rock, possibly mica schist

Banded metamorphic rock, likely gneiss or banded amphibolite

Quartz–feldspar–biotite gneiss or amphibolite; exact identification requires thin-section or mineral tests

Rounded river pebble, likely basalt or andesite

Fine-grained mafic volcanic rock; commonly plagioclase ± pyroxene, olivine, and iron oxides

Conglomeratic gravel / lithified alluvial deposit

Polymictic conglomerate or pebble-rich sandstone (likely weakly cemented)

Iron-rich meteorite candidate

Unclassified stony-iron or ordinary chondrite candidate

Jasper with Hematite inclusions

Silicon Dioxide (SiO2) with Ferric Oxide (Fe2O3)

Likely river-worn dark stone (possibly basalt or shale)

Indeterminate; likely fine-grained basalt (plagioclase–pyroxene), though slate/shale is also possible

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

Weathered conglomeratic or breccia cobble

Lithified polymictic conglomerate/breccia, likely iron-stained siliciclastic rock

Weathered granitic rock (likely granite or granodiorite)

Granite–granodiorite; mainly quartz, feldspar, and mica/hornblende

Geode with Quartz and Chalcedony

Silicon Dioxide (SiO2)

Tumbled brown-and-cream stone, likely jasper or chert

Microcrystalline quartz (SiO₂), probably jasper/chert; exact identification requires testing

Fossilized Bored Limestone

Limestone with Ichnofossils (Gastrochaenolites or Entobia)

Sandstone

Arenite (primarily SiO2)

Rounded sandstone pebble

Clastic sandstone, likely quartz–feldspar-rich (exact identification requires testing)

Granitic Gneiss

Gneiss (High-grade Metamorphic Rock)

Quartz geode or quartz-bearing rock

Quartz (SiO₂), likely in a chalcedony- or basalt-hosted cavity